1. Field of the Invention
This invention relates generally to high pressure inflatable air bags utilized for lifting and sealing, and more specifically, this invention relates to an external clamping device to grip inflatable air bags to permit desired positioning of the air bags without damaging the expandable material of which they are formed.
2. Description of the Prior Art
High pressure inflatable air bags have become useful in a variety of applications, including such applications as the lifting of weight, the forcible separation of adjacent masses and the sealing of large tanks and conduits. These air bags have the advantage of being able to fit in a space of only a few inches, prior to inflation. They also have the advantage of being able to generate very large forces without cumbersome and awkward mechanical equipment.
Generally, these air bags are formed from a resilient or expandable material, such as rubber, reinforced with a strengthening arrangement, such as a wire matrix.
While such high pressure inflatable air bags have many advantages, they must still be properly positioned in order to be able to produce the desired results. Thus, when an air bag is to be positioned in a very narrow space, such as in a missile silo or a rock quarry, or is to be positioned in a number of hard to reach locations such as under a low slung large vehicle, difficulties are frequently encountered. There are also difficulties in positioning the air bags for sealing large vessels or pipes.
Attempts have been made to mold a rubber strap or fabric reinforced strap into the air bags to provide a handle for positioning. One of the problems encountered in these approaches is the limited strength of the strap. Efforts to strengthen the strap have created problems in the manufacture of the bag. Thus, one is left with a relatively weak strap, which cannot be replaced when it breaks.
Another approach has been to try and mold clamps into the material of the air bag itself. The problem with this approach is that it has weakened the air bag at that point, so that either the air bag fails or the clamp is ripped out, rendering the air bag unusable.
Since such inflatable air bags require an expandable material, the expandable material must be relatively soft. Rubber is commonly used as the expandable material, and any rubber that provides the desired expansion is sufficiently soft to be subject to cutting or tearing, presenting the possibility of leakage when the air bag is pressurized.
Also, since the problem is primarily encountered in positioning the air bags in relatively small spaces, any clamping arrangement must have a relatively low profile in order to permit the air bag with attached clamps to fit into the desired space. This means that the relatively high clamping force must be achieved by a device that has a relatively low profile or total thickness, and which does not jeopardize the material of the air bag.